Mitochondria-specific RNA-modifying enzymes responsible for the biosynthesis of the wobble base in mitochondrial tRNAs - Implications for the molecular pathogenesis of human mitochondrial diseases
Mitochondria-specific RNA-modifying enzymes responsible for the biosynthesis of the wobble base in mitochondrial tRNAs - Implications for the molecular pathogenesis of human mitochondrial diseases
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DOI：
10.1074/jbc.m409306200
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发表时间：
2005-01-14
影响因子：
4.8
通讯作者：
Suzuki, T
中科院分区：
文献类型：
--
作者：
Umeda, N;Suzuki, T;Suzuki, T
人线粒体（mt）tRNA（Lys）在其反密码子摆动位置有一个含牛磺酸的修饰尿苷，即5-牛磺酸甲基-2-硫尿苷（taum（5）s（2）U）。我们以前发现，携带A8344 G突变的线粒体tRNA（Lys）来自与破碎红纤维相关的肌阵挛癫痫（MERRF）患者的细胞，缺乏taum（5）s（2）U修饰。在这里，我们描述了一个tRNA修饰酶MTU 1（线粒体tRNA特异性2-硫代尿苷酶1），是负责在人类和酵母mt tRNA的摆动位置的2-巯基化的鉴定和表征。酵母MTU 1基因的破坏消除了mt tRNA的2-硫代修饰，并损害了线粒体蛋白质合成，从而导致呼吸活性降低。此外，当负责修饰的尿苷的C5取代基的MTO 1或MSS 1与MTU 1一起被沿着破坏时，观察到线粒体活性的严重得多的降低。因此，C5和2-硫代修饰在促进有效的同源密码子解码中协同作用。小干扰RNA对HeLa细胞中MTU 1的部分失活也降低了它们的耗氧量，并导致线粒体膜电位缺陷，这与MERRF中观察到的表型特征相似。
Human mitochondrial (mt) tRNA(Lys) has a taurine-containing modified uridine, 5-taurinomethyl-2-thiouridine (taum(5)s(2)U), at its anticodon wobble position. We previously found that the mt tRNA(Lys), carrying the A8344G mutation from cells of patients with myoclonus epilepsy associated with ragged-red fibers (MERRF), lacks the taum(5)s(2)U modification. Here we describe the identification and characterization of a tRNA-modifying enzyme MTU1 (mitochondrial tRNA-specific 2-thiouridylase 1) that is responsible for the 2-thiolation of the wobble position in human and yeast mt tRNAs. Disruption of the yeast MTU1 gene eliminated the 2-thio modification of mt tRNAs and impaired mitochondrial protein synthesis, which led to reduced respiratory activity. Furthermore, when MTO1 or MSS1, which are responsible for the C5 substituent of the modified uridine, was disrupted along with MTU1, a much more severe reduction in mitochondrial activity was observed. Thus, the C5 and 2-thio modifications act synergistically in promoting efficient cognate codon decoding. Partial inactivation of MTU1 in HeLa cells by small interference RNA also reduced their oxygen consumption and resulted in mitochondria with defective membrane potentials, which are similar phenotypic features observed in MERRF.